ABSTRACT:
In this paper,
a new power frequency model for unified power flow controller (UPFC) is suggested
with its dc link capacitor dynamics included. Four principal control strategies
for UPFC series element main control and their impacts on system stability are
discussed. The main control of UPFC series element can be realized as a
combination of the four control functions. The supplementary control of UPFC is
added for damping power oscillation. The integrated UPFC model has then been
incorporated into the conventional transient and small signal stability
programs with a novel UPFC-network interface. Computer tests on a 4-generator interconnected
power system show that the suggested UPFC power frequency model and the UPFC-
network interface method work very well. The results also show that the
suggested UPFC control strategy can realize power flow control fairly well and
improve system dynamic performance significantly.
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1. Transmission line with UPFC installed.
CONTROL SYSTEM:
Fig.
2. The main control and phasor diagram.
EXPECTED SIMULATION RESULTS:
Fig.
3. Plots of case 1a.
Fig.
4. Plots of case 1b.
Fig.
5. Plots of case 1c.
Fig.
6. Effects of supplementary control.
Fig.
7. Results of the suggested control scheme.
CONCLUSION:
The suggested UPFC power frequency model
and the developed UPFC-network interface method work very well in the study of
power system dynamics with satisfied convergence and accuracy. Four principal
main control strategies are discussed and the computer tests results support
the discussion conclusion very well. The constant power flow control is good for
steady state control and the constant series compensation control is useful for
first swing stability. The supplementary control is very efficient in damping
intcrarea power oscillation. The suggested UPFC control can realize the desired
control strategy flexibly and improve system dynamic performance significantly.
REFERENCES:
[1] L. Gyugyi, “Unified Power-Flow
Control Concept for Flexible AC Transmission Systems,” IEE Proceedings-C,
vol. 139, no. 4, pp. 323–331, July 1992.
[2] I. Papic, P. Zunko, and D. Povh, “Basic
Control of Unified Power Flow Controller,” IEEE Trans. on Power Systems,
vol. 12, no. 4, pp. 1734–1739, Nov. 1997.
[3] R. Mihalic, P. Zunko, and D. Povh,
“Improvement of Transient Stability Using Unified Power Flow Controller,” IEEE
Trans. on Power Delivery, vol. 11, no. 1, pp. 485–491, Jan. 1996.
[4] K. S. Smith, L. Ran, and J. Penman,
“Dynamic Modeling of a Unifed Power Flow Controller,” IEE Proc.-Gener.
Transm. Distrib., vol. 144, no. 1, pp. 7–12, Jan. 1997.
[5] M. Noroozian, L. Angquist, and M.
Ghandhari, et al., “Improving Power System Dynamics by Series-connected
FACTS devices,” IEEE Trans. on Power Delivery, vol. 12, no. 4, pp.
1635–1641, Oct. 1997.
